A number of different methods for collecting oil from a water surface are previously known. Most commonly is a boom launched and a separate skimmer used for the removal of oil being collected in the rearmost part of the boom. The drawback with this type of booms is that they cannot be towed forward at high speed, as the oil will be drawn into the water underneath the boom. Another drawback with booms of prior art is that the skimmer for collecting the oil on the water surface often collects a lot of water, and occasionally also a lot of air, at the same time. The oil concentration is simply too low and the sea too rough, so that the skimmer intake from time to time is above the sea surface.
Most prior art booms are designed for concentrating and collecting oil spill at the sea surface, that is oil which substantially is not mixed into water and is floating on the surface as a slick. Examples of such booms adapted for removing oil spill at a high relative speed, is the Ocean Buster by NOFI and the Active Oil Trawl by Norlense. These booms only collect oil on the surface in fairly calm weather and at wind generated waves less than 2.5-3 meters height. The applicable parameter in this context is the sum of the relative towing speed and the orbital water velocity of the waves. Patent documents WO 8202912 and U.S. Pat. No. 5,200,066 describe two booms for collecting oil spill at the sea surface, both comprising means for creating a vortex motion in the water in order to concentrate the oil before it is collected.
Experience does however indicate that mechanical dispersion of the oil slick (the dispersion into oil drops) starts already at a water current speed exceeding 0.5 m/s (1 knot) relative to the oil, or when the waves break. There is thus a reason to assume that there will be certain concentration of oil dispersed at the water surface even at a moderate breeze, and that said dispersion will increase with increasing wave height. For more information, see for example Gerald A. L. Delvigne: Natural dispersion of Oil by Different Sources of Turbulence”, Joint Oil Spill Conf. 1993, pp 415-419. Experience further shows that substantially all the oil will be disintegrated to drops (natural dispersion) at wave heights over 3 m, thereby making attempts to collect oil by using booms of today almost pointless.